1. Field of the Invention
The invention relates to an improved rotary valve for fluid control, and, more particularly, to a rotary valve of the so-called eccentric type.
2. Description of the Prior Art
There have been many different types of spherical faced plugs used in prior art valves that are constructed for movement into and out of engagement with a seat port. One example of such a prior art valve is shown in the Baumann U.S. Pat. No. 3,623,696.
The plug that is disclosed in the aforementioned patent and an arm which extends therefrom are of a solid one unit construction. The valve plug and arm are rotatable eccentrically relative to a seat port by means of an actuator shaft mounted in the wall portion of a valve chamber.
As the actuator shaft is rotated in one direction, it rotates the spherical face of the plug eccentrically relative to the seat face of the seat port. when a portion of the plug comes in contact with the seat face, the arm commences to bend along its longitudinal axis, and this results in the spherical face of the plug being rubbed against the seat face as continued rotation of the plug toward its closed valve position occurs.
A similar rubbing action as that just described takes place between the spherical contact portion of the plug and the seat face of the seat port when the plug is moved toward its open position.
From the aforementioned description it can be seen that a rubbing force is applied on a small segment of the seat port during each successive port closing and port opening operation. This rubbing action thus causes or tends to cause wear to occur between the rubbing surface of the spherical plug and the surfaces of the seat port. The greatest wear occurs where the segments of the plug and the seat port portion are first brought into contact with one another as the valve is closed.
As the valve continues to cycle between an open and closed position, this action results in an uneven wear between the plug and the seat port and results in increasing leakage between the plug and the seat port.
Further, the parts of such a prior art valve must be produced with fine tolerances, and its parts assembled in a precise actuating manner, in order to procure tight sealing between its plug and seat port.
A Zeigler et al. U.S. Pat. No. 3,191,906 shows another prior art rotary valve, as does the Myers U.S. Pat. No. 3,963,211. Although such valves doubtless have utility from certain standpoints, there has still remained a need for a tight closing, long wearing, easily adjusted, reliable, and economically producible eccentric rotary valve.